Darkness Returns
by sedatetoucan
Summary: My first time on here, so please be gentle. The Emperor returns with new ghouls and new allies. The Shane Gang have to fight for their lives and that of everyone in Slugterra. The Emperor has a new and dangerous plan; but with the help of an incredibly experienced slinger and a set of insanely powerful slugs, they might just win. I'm not the best writer ever, please forgive me.
1. Info

**Information and Explanation  
**

Firstly, I just want to say that I'm not the most experienced writer, so I hope you can bare with me a little.

This is a Slugterra and Thunderbirds crossover, but it's more a Slugterra fanfic with references to Thunderbirds, most notably in some new slugs. All of which are some crossover designs by Langodan on DeviantArt. You should check them out to get what I mean. The designs in this story are basically those (don't worry, I asked for permission to use their designs). This story is set in Slugterra, but with references to Thunderbirds Are Go, the reboot (I'll be referring to it as TAG from now on), so if you haven't seen either series, I highly recommend you do. Mainly because the story will reference the new villain from Season 2, and to be honest, he hasn't gotten much exposure as of now, so when I write the story, the character will be based on the small amount of teaser content. So if you are reading this after season 2 has aired, please forgive me.

The story will take place after Into the Shadows, so may contain spoilers. It will also have an OC of mine featured, as well as some far from canon tech and ideas, but that's the beauty of fanfiction!

So? What do you think? I haven't actually written it yet, as I don't want to write a story no one is interested in. If you would like me to properly write it, show you are interested by leaving a review. You can even include ideas you may have, as well as some tips if you have any. I tend to be really impatient, so I might write the story without getting any reviews, but that's me. If I do end up writing it, updates will be very irregular.

Well, I guess the waiting game begins for both me and you...

Edit: I've decided to start writing the story, mainly because I need to let my ideas out. You can expect the Prologue soon. Edits will still be very irregular.


	2. Prologue

**Prologue**

 **I do not own any of the characters, except my OC (who will appear later). This takes place after Into the Shadows, so spoiler alert. Also, what do you think of my cover? Get the reference? There are also bound to be some references strewn throughout the story. See if you can find them all.**

* * *

Tad was angry. Angry that he had just been beaten by Eli. He was so sure he would win, but alas... Here he was, gliding through the Deep Caverns. He felt nothing, but he knew the Dark Energy was slowly corrupting and maddening him from the inside. He had a few ghouls left, and Pieper, but she was of no use down here, and he had no plans to ghoul her. He had landed soon after falling into the Deep Caverns, but decided to move elsewhere, the Darkbane were not cooperating.

Up ahead, Tad could see a wall of loose looking rocks. Could he have reached the edge of the Deep Caverns already? He had been flying for over an hour now, sometimes using his Hoverblade to pull him forward. Wondering, he loaded a Hop Jack into his blaster and fired it at a particularly loose boulder. It blew the boulder to smithereens and left a hole in its place. It wasn't quite large enough for him to fit through, but a Harmashelt later and Tad was soaring into a small adjoining cavern. It was round and had a hole at the top, leading to what he hoped was another part of Slugterra. He landed quietly on a ledge, and that's when he noticed...

* * *

The Emperor slowly opened his eyes when he heard the explosion from Tad barging in. He watched as a ginger-haired, young boy soared through the air and landed not far from him. The boy seemed oblivious to the fact that he was being watched. The Emperor didn't often get visitors, especially young boys. The last time he had met a young boy, it had been Eli, and he had beaten him, locked him in this cavern, away from Slugterra, away from the place he wanted to destroy. The Emperor would do anything to get back up to Peach Blossom Spring Cavern. Even if it meant working with the boy, who seemed as angry has he.

* * *

Tad was shocked to find anyone down here. The man who sat on the throne not far from where he was standing was staring at him with his red eyes, unblinking. Tad slowly approached. He looked like someone who would have similar plans to him. Tad was about to speak when the man suddenly started.

'What are you doing here, young boy?'

Tad was flabbergasted but gave a brief reply.

'I-I fell down here.'

'How, young boy?'

'I don't really know.'

'You shouldn't be here. This is my territory. Although, I must get back up there. I have unfinished business to complete.'

'You do?'

'Yes, I must reclaim what is rightfully mine, or destroy it entirely.'

'You mean Slugterra?'

'You know, don't you? You have ghouls...'

They stared at each other for a while, before Tad spoke up.

'So uhh...I didn't catch your name.'

'I didn't throw it.' The Emperor replied calmly. 'But you can call me your master, The Emperor.'

'And I'm Tad... WAIT WHAT?! I'M NOT YOUR SERVANT!'

'You are now. Anyone who meets me here is. And if you have a problem with that, well too bad. I have ways of making you work for me if you don't help me get back up into Slugterra.'

'Fine, as long as it means I get to get revenge on someone I hate.'

'That's exactly what I want as well.'

They stopped, and Tad thought of something. If he could get the Emperor up into Slugterra, he would be freed. Or he could even continue to work for him, as long as he could take out Eli and the Shane Gang once and for all. Then they could rule Slugterra.

'So, uhh, I have an idea on how we could get back up to Slugterra.' Tad said hopefully.

'Do you now? Let me hear it.'

Just as Tad was about to start explaining, there was a faint "bong" sound and a small flash of light from the hole at the top of the cavern.

'The Guardian Gate? Opened?' The Emperor stood up, roughly pushed Tad aside and took a quick glance up the hole. Then, without warning, he jumped all the way up to the mouth of the hole, which Tad then saw was actually a tunnel leading up to what he hoped was Slugterra. The Emperor disappeared up the tunnel.

Tad turned to his slug, Pieper, who was sleeping.

'Hey girl, wake up, I need you to help me with some ghouls.'

Pieper woke up slowly, blinked and snapped to attention.

'I need to ride this Hoverblade. Think you could manage that?'

Peiper gave a swift nod, sang her hypnotising song at the Hoverblade in question, then hopped back onto Tad's shoulder, continuing to sing quietly. Tad loaded the Hoverblade into his blaster, then fired it at the tunnel opening. It transformed, spread its wings and turned around to come speeding back at Tad.

'I hope your charm worked, Peiper.'

Tad jumped high as the Hoverblade came swooping in low, and he landed lightly on its back. He then bent down and held on tight as the Hoverblade sped up the tunnel, leaving the Deep Caverns behind him.

* * *

Soon, Tad reached the Emperor, who was climbing the tunnel surprisingly fast. He said nothing as Tad passed him, but he looked annoyed. Tad flew out of the top of the tunnel. The opening was surrounded by 12 pedestals that looked like they were made for supporting slugs, but there were none on any of them now. The Hoverblade shrunk, and Tad landed outside the ring of pedestals. The Emperor climbed out soon after.

'Kid! How dare you speed ahead of me!"

'Sorry Emperor, you were just too slow.'

Saying this only made the Emperor madder.

'YOU TRULY ARE AN IN-'

But he stopped. A man had stepped out of the shadows. He was clutching the Elementals, two in each hand.

'Well, what do we have here?' the man said in a slightly muffled voice. But that was expected, given what he was wearing on his face. He had a mask that completely covered his mouth and extremely tinted goggles that obscured his eyes. Black and orange armour covered his body, though his arms were exposed. He had various tools at his side and a cannon like assembly on his back. His brown hair was stuck up almost like a small mohawk. He was clearly not from Slugterra.

'What are these... creatures?' He asked the Emperor and Tad, holding up the Elementals.

'They're slugs. They transform into giant battle beasts when fired at 100mph.' Tad replied calmly.

'They do, do they? Slugs certainly don't where I come from.'

That's when it hit Tad.

'You're from the Surface, aren't you?'

'Very clever, you know your stuff.'

'I'm kinda from there too.'

'Good to know.'

'So who are you?'

There was a pause. Then the stranger replied.

'I am The Mechanic. I take what I want, from who I want, whenever I want it.'

* * *

 **How's THAT for a prologue?! Sorry, I enjoy ending with a cliffhanger. If you are wondering about when this is set, treat it as though both series are set at the same time (I know, TAG is set in 2060, and Slugterra doesn't really have a time mentioned.). It'll be a while before the next chapter is to be released, so be prepared for a long wait.**


End file.
